Elastomeric compounds useful in the fabrication of automotive hoses include chlorinated polyethylene, chlorosulfonated polyethylene and epichlorohydrin elastomers as disclosed for example in U.S. Pat. No. 5,683,773. Compounds made using these polymers possess good mechanical properties, low compression set, good low temperature flexibility, and good dynamic fatigue resistance. These compounds also exhibit excellent aging, weathering, chemical and ozone resistance due to their saturated backbones, and the polarity contributed by the chlorine and ether components provide good oil swell resistance.
Newer specifications for automotive hose compounds require air and oil resistance at temperatures of up to 175° C. Compounds comprising chlorinated polyethylene and chlorosulfonated polyethylene compounds cannot be used at these higher temperatures. Copolymers and terpolymers of ethylene and alkyl acrylates are useful as hose compounds at higher temperatures, but are expensive to use.
U.S. Pat. No. 4,759,388 discloses a hose comprising inner and outer tubes of an acrylic rubber. The acrylic rubber may be acrylic acid lower alkyl ester alone, or the ester as a main component polymerized with copolymerizable monomer under the presence of a crosslinking agent. The acrylic rubber may be a copolymer comprising acrylic acid lower alkyl ester as a main component and ethylene and vinyl acetate as copolymer components. The crosslinking agent may be an acrylic acid derivative having one of carboxyl group, epoxy group and chlorine atoms, or a methacrylic acid derivative.
European Patent No. 0370361 discloses soft, elastic polymer mixtures based on crosslinked, particulate alkyl acrylate rubbers and hydrolyzed ethylene vinyl acetate copolymers.
U.S. Pat. No. 5,274,035 discloses ethylene vinyl acetate compositions and medical tubing made therefrom. The compositions comprise a major amount of ethylene vinyl acetate and a minor amount of one or more other polymers. The other polymers may include a terpolymer of an alpha olefin, an acrylic ester, and an olefinically unsaturated dicarboxylic acid, such as ethylene/methyl acrylate/maleic anhydride. Suitable ethylene vinyl acetate comprises from about 5 to about 50 percent by weight of vinyl acetate.
U.S. Pat. No. 5,492,971 discloses a curable ethylene copolymer blend composition which is a blend of an ethylene dipolymer, an ionomer of an ethylene unsaturated acid copolymer, and a peroxide curing agent. The ethylene dipolymer may be ethylene vinyl acetate. The ionomer may be ethylene/methyl acrylate/ethyl hydrogen maleate.
Paper No. 187 presented at the meeting of the Rubber Division, American Chemical Society, Orlando, Fla., Sep. 21 through 24, 1999, discloses the use of ethylene vinyl acetate in compounds suitable for use in automotive hoses. The ethylene vinyl acetate compounds disclosed utilize enhanced viscosity ethylene vinyl acetate that has been partially crosslinked via peroxide or radiation. The ethylene vinyl acetate compounds therein are shown to have superior high temperature property retention as compared with compounds of chlorosulfonated polyethylene or ethylene/methyl acrylate terpolymer.